Adoptive T cell therapy has been shown to be effective at eradicating tumors in murine models. Yet, this therapeutic strategy has not been successfully translated to the clinic to treat human malignancy. Most studies have focused on therapy with infusion of cytotoxic T lymphocytes (CTL). While CTL have been shown to be functional following infusion, their capabilities of eradicating tumor are diminished due to a number of reasons including a short life span. Concomitant activation of the T helper cell (Th) is necessary for a CTL persistence. In fact, Th cell infusions alone can activate endogenous CTL immunity. The 2 predominant subtypes of Th cells are Thl and Th2. Thl cells elicit CTL immunity and Th2 cells elicit B cell immunity. The importance of humoral immunity against cancer is evident by the current clinical use of Herceptin. Based on these observations, it is hypothesized that adoptive T cell therapy of Th can be an effective therapy for the treatment of HER-2/neu-overexpressing human breast malignancies. Yet many of the principles of adoptive T cell therapy with Th remain unknown. A clinically relevant mouse model (neu-transgenic mouse) is available to identify these principles. Furthermore, studies have recently demonstrated that tumor-specific Th cells can be expanded ex vivo from patients with HER-2/neu-overexpressing cancers. This proposal outlines the pre-clinical studies needed to establish the role of Thl and Th2 T helper cell infusion in the eradication of neu-overexpressing tumors in a murine model and will identify the culture conditions most effective in expanding HER2-specific Th cells while retaining antigen-specific function. The specific aims of this proposal are: (1) To examine the therapeutic efficacy of adoptively transferred Thl and Th2 CD4 T cells against neu-mediated tumors in the neu-transgenic mouse, and (2) To determine optimal culture conditions for preferential expansion of antigen-specific Thl T cells or Th2 T cells from the blood of patients with HER2-overexpressing cancers Results from the proposed studies will lead to a Phase I trial of HER2-specific adoptive immunotherapy for the treatment of advanced stage HER2 overexpressing malignancies.